Your First AI application

Going forward, AI algorithms will be incorporated into more and more everyday applications. For example, you might want to include an image classifier in a smart phone app. To do this, you'd use a deep learning model trained on hundreds of thousands of images as part of the overall application architecture. A large part of software development in the future will be using these types of models as common parts of applications.

In this project, you'll train an image classifier to recognize different species of flowers. You can imagine using something like this in a phone app that tells you the name of the flower your camera is looking at. In practice you'd train this classifier, then export it for use in your application. We'll be using this dataset from Oxford of 102 flower categories, you can see a few examples below.

The project is broken down into multiple steps:

• Load the image dataset and create a pipeline.
• Build and Train an image classifier on this dataset.
• Use your trained model to perform inference on flower images.

We'll lead you through each part which you'll implement in Python.

When you've completed this project, you'll have an application that can be trained on any set of labeled images. Here your network will be learning about flowers and end up as a command line application. But, what you do with your new skills depends on your imagination and effort in building a dataset. For example, imagine an app where you take a picture of a car, it tells you what the make and model is, then looks up information about it. Go build your own dataset and make something new.

Import Resources

# TODO: Make all necessary imports.
import warnings
warnings.filterwarnings('ignore')

%matplotlib inline
%config InlineBackend.figure_format = 'retina'

import json
import seaborn as sns
import time
import numpy as np
import matplotlib.pyplot as plt

#import keras
import tensorflow as tf

import tensorflow_hub as hub
import tensorflow_datasets as tfds
tfds.disable_progress_bar()

import logging
logger = tf.get_logger()
logger.setLevel(logging.ERROR)

print('Using:')
print('\t\u2022 TensorFlow version:', tf.__version__)
print('\t\u2022 tf.keras version:', tf.keras.__version__)
print('\t\u2022 Running on GPU' if tf.test.is_gpu_available() else '\t\u2022 GPU device not found. Running on CPU')

Using:
	• TensorFlow version: 2.0.0
	• tf.keras version: 2.2.4-tf
	• GPU device not found. Running on CPU

Load the Dataset

Here you'll use tensorflow_datasets to load the Oxford Flowers 102 dataset. This dataset has 3 splits: 'train', 'test', and 'validation'. You'll also need to make sure the training data is normalized and resized to 224x224 pixels as required by the pre-trained networks.

The validation and testing sets are used to measure the model's performance on data it hasn't seen yet, but you'll still need to normalize and resize the images to the appropriate size.

# Load the dataset along with its info
dataset, dataset_info = tfds.load('oxford_flowers102', with_info=True, as_supervised=True)

# If you need to split the dataset into training, validation, and test sets, specify the splits
training_set, validation_set, test_set = tfds.load('oxford_flowers102', split=['train', 'validation', 'test'], as_supervised=True)

Explore the Dataset

dataset_info

tfds.core.DatasetInfo(
    name='oxford_flowers102',
    version=2.0.0,
    description='
The Oxford Flowers 102 dataset is a consistent of 102 flower categories commonly occurring
in the United Kingdom. Each class consists of between 40 and 258 images. The images have
large scale, pose and light variations. In addition, there are categories that have large
variations within the category and several very similar categories.

The dataset is divided into a training set, a validation set and a test set.
The training set and validation set each consist of 10 images per class (totalling 1020 images each).
The test set consists of the remaining 6149 images (minimum 20 per class).
',
    homepage='https://www.robots.ox.ac.uk/~vgg/data/flowers/102/',
    features=FeaturesDict({
        'file_name': Text(shape=(), dtype=tf.string),
        'image': Image(shape=(None, None, 3), dtype=tf.uint8),
        'label': ClassLabel(shape=(), dtype=tf.int64, num_classes=102),
    }),
    total_num_examples=8189,
    splits={
        'test': 6149,
        'train': 1020,
        'validation': 1020,
    },
    supervised_keys=('image', 'label'),
    citation="""@InProceedings{Nilsback08,
       author = "Nilsback, M-E. and Zisserman, A.",
       title = "Automated Flower Classification over a Large Number of Classes",
       booktitle = "Proceedings of the Indian Conference on Computer Vision, Graphics and Image Processing",
       year = "2008",
       month = "Dec"
    }""",
    redistribution_info=,
)

# TODO: Get the number of examples in each set from the dataset info.
num_training_examples = dataset_info.splits['train'].num_examples
num_validation_examples = dataset_info.splits['validation'].num_examples
num_test_examples = dataset_info.splits['test'].num_examples

print('There are {:,} images in the training set'.format(num_training_examples))
print('There are {:,} images in the validation set'.format(num_validation_examples))
print('There are {:,} images in the test set'.format(num_test_examples))
                                                     
# TODO: Get the number of classes in the dataset from the dataset info.
num_classes = dataset_info.features['label'].num_classes
print('There are {:,} classes in our dataset'.format(num_classes))

There are 1,020 images in the training set
There are 1,020 images in the validation set
There are 6,149 images in the test set
There are 102 classes in our dataset

# TODO: Print the shape and corresponding label of 3 images in the training set.
for image, label in training_set.take(3):
    print('Image shape:', image.shape, 'label:', label.numpy())

Image shape: (500, 667, 3) label: 72
Image shape: (500, 666, 3) label: 84
Image shape: (670, 500, 3) label: 70

# TODO: Plot 1 image from the training set. Set the title 
# of the plot to the corresponding image label. 
for image, label in training_set.take(1):
    image = image.numpy()
    label = label.numpy()

plt.imshow(image)
plt.title(str(label))
plt.show()

Label Mapping

You'll also need to load in a mapping from label to category name. You can find this in the file label_map.json. It's a JSON object which you can read in with the json module. This will give you a dictionary mapping the integer coded labels to the actual names of the flowers.

with open('label_map.json', 'r') as f:
    class_names = json.load(f)

# TODO: Plot 1 image from the training set. Set the title 
# of the plot to the corresponding class name. 

for image, label in training_set.take(1):
    plt.imshow(image.numpy())
    label=label.numpy()
    plt.title(class_names[str(label+1)])
    plt.colorbar()
    plt.show()

Create Pipeline

# TODO: Create a pipeline for each set.

IMAGE_RES = 224

def format_image(image, label):
    image = tf.cast(image, tf.float32)
    image = tf.image.resize(image, (224, 224))
    image = (image / 255)
    return image, label

BATCH_SIZE = 32

training_batches = training_set.cache().shuffle(num_training_examples//4).map(format_image).batch(BATCH_SIZE).prefetch(1)

validation_batches = validation_set.cache().map(format_image).batch(BATCH_SIZE).prefetch(1)

test_batches = test_set.cache().map(format_image).batch(BATCH_SIZE).prefetch(1)

Build and Train the Classifier

Now that the data is ready, it's time to build and train the classifier. You should use the MobileNet pre-trained model from TensorFlow Hub to get the image features. Build and train a new feed-forward classifier using those features.

We're going to leave this part up to you. If you want to talk through it with someone, chat with your fellow students!

Refer to the rubric for guidance on successfully completing this section. Things you'll need to do:

• Load the MobileNet pre-trained network from TensorFlow Hub.
• Define a new, untrained feed-forward network as a classifier.
• Train the classifier.
• Plot the loss and accuracy values achieved during training for the training and validation set.
• Save your trained model as a Keras model.

We've left a cell open for you below, but use as many as you need. Our advice is to break the problem up into smaller parts you can run separately. Check that each part is doing what you expect, then move on to the next. You'll likely find that as you work through each part, you'll need to go back and modify your previous code. This is totally normal!

When training make sure you're updating only the weights of the feed-forward network. You should be able to get the validation accuracy above 70% if you build everything right.

Note for Workspace users: One important tip if you're using the workspace to run your code: To avoid having your workspace disconnect during the long-running tasks in this notebook, please read in the earlier page in this lesson called Intro to GPU Workspaces about Keeping Your Session Active. You'll want to include code from the workspace_utils.py module. Also, If your model is over 1 GB when saved as a checkpoint, there might be issues with saving backups in your workspace. If your saved checkpoint is larger than 1 GB (you can open a terminal and check with ls -lh), you should reduce the size of your hidden layers and train again.

# TODO: Build and train your network.

URL = "https://tfhub.dev/google/tf2-preview/mobilenet_v2/feature_vector/4"

feature_extractor = hub.KerasLayer(URL, input_shape=(224, 224,3), trainable = False)


model = tf.keras.Sequential([
        feature_extractor,
        tf.keras.layers.Dense(num_classes, activation = 'softmax')
])

model.summary()

model.compile(optimizer='adam',
              loss='sparse_categorical_crossentropy',
              metrics=['accuracy'])

EPOCHS = 5

early_stopping = tf.keras.callbacks.EarlyStopping(monitor='val_loss', patience=5)

history = model.fit(training_batches,
                    epochs=EPOCHS,
                    validation_data=validation_batches,  callbacks = [early_stopping])

Model: "sequential"
_________________________________________________________________
Layer (type)                 Output Shape              Param #   
=================================================================
keras_layer (KerasLayer)     (None, 1280)              2257984   
_________________________________________________________________
dense (Dense)                (None, 102)               130662    
=================================================================
Total params: 2,388,646
Trainable params: 130,662
Non-trainable params: 2,257,984
_________________________________________________________________
Epoch 1/5
32/32 [==============================] - 15s 465ms/step - loss: 4.2293 - accuracy: 0.1157 - val_loss: 0.0000e+00 - val_accuracy: 0.0000e+00
Epoch 2/5
32/32 [==============================] - 13s 408ms/step - loss: 2.0757 - accuracy: 0.6833 - val_loss: 2.0167 - val_accuracy: 0.6373
Epoch 3/5
32/32 [==============================] - 13s 413ms/step - loss: 1.1040 - accuracy: 0.8951 - val_loss: 1.5483 - val_accuracy: 0.7294
Epoch 4/5
32/32 [==============================] - 13s 413ms/step - loss: 0.6636 - accuracy: 0.9578 - val_loss: 1.3061 - val_accuracy: 0.7412
Epoch 5/5
32/32 [==============================] - 13s 407ms/step - loss: 0.4439 - accuracy: 0.9833 - val_loss: 1.1732 - val_accuracy: 0.7735

# TODO: Plot the loss and accuracy values achieved during training for the training and validation set.

acc = history.history['accuracy']
val_acc = history.history['val_accuracy']

loss = history.history['loss']
val_loss = history.history['val_loss']

epochs_range = range(EPOCHS)

plt.figure(figsize=(8, 8))
plt.subplot(1, 2, 1)
plt.plot(epochs_range, acc, label='Training Accuracy')
plt.plot(epochs_range, val_acc, label='Validation Accuracy')
plt.legend(loc='lower right')
plt.title('Training and Validation Accuracy')

plt.subplot(1, 2, 2)
plt.plot(epochs_range, loss, label='Training Loss')
plt.plot(epochs_range, val_loss, label='Validation Loss')
plt.legend(loc='upper right')
plt.title('Training and Validation Loss')
plt.show()

Testing your Network

It's good practice to test your trained network on test data, images the network has never seen either in training or validation. This will give you a good estimate for the model's performance on completely new images. You should be able to reach around 70% accuracy on the test set if the model has been trained well.

# TODO: Print the loss and accuracy values achieved on the entire test set.
loss, accuracy = model.evaluate(test_batches)

print('\nLoss on the TEST Set: {:,.3f}'.format(loss))
print('Accuracy on the TEST Set: {:.3%}'.format(accuracy))

193/193 [==============================] - 41s 214ms/step - loss: 1.2758 - accuracy: 0.7426

Loss on the TEST Set: 1.276
Accuracy on the TEST Set: 74.256%

Save the Model

Now that your network is trained, save the model so you can load it later for making inference. In the cell below save your model as a Keras model (i.e. save it as an HDF5 file).

# TODO: Save your trained model
#tf.saved_model.save(model, "flower_model")
# TODO: Save your trained model as a Keras model.
model_path = './flowers_model.h5'
model.save(model_path)

Load the Keras Model

Load the Keras model you saved above.

# TODO: Load the Keras model
#model = tf.keras.models.load_model('flower_model')

# TODO: Load the Keras model

reloaded_model = tf.keras.models.load_model(model_path,custom_objects={'KerasLayer':hub.KerasLayer})
reloaded_model.summary()

Model: "sequential"
_________________________________________________________________
Layer (type)                 Output Shape              Param #   
=================================================================
keras_layer (KerasLayer)     (None, 1280)              2257984   
_________________________________________________________________
dense (Dense)                (None, 102)               130662    
=================================================================
Total params: 2,388,646
Trainable params: 130,662
Non-trainable params: 2,257,984
_________________________________________________________________

Inference for Classification

Now you'll write a function that uses your trained network for inference. Write a function called predict that takes an image, a model, and then returns the top $K$ most likely class labels along with the probabilities. The function call should look like:

probs, classes = predict(image_path, model, top_k)

If top_k=5 the output of the predict function should be something like this:

probs, classes = predict(image_path, model, 5)
print(probs)
print(classes)
> [ 0.01558163  0.01541934  0.01452626  0.01443549  0.01407339]
> ['70', '3', '45', '62', '55']

Your predict function should use PIL to load the image from the given image_path. You can use the Image.open function to load the images. The Image.open() function returns an Image object. You can convert this Image object to a NumPy array by using the np.asarray() function.

The predict function will also need to handle pre-processing the input image such that it can be used by your model. We recommend you write a separate function called process_image that performs the pre-processing. You can then call the process_image function from the predict function.

Image Pre-processing

The process_image function should take in an image (in the form of a NumPy array) and return an image in the form of a NumPy array with shape (224, 224, 3).

First, you should convert your image into a TensorFlow Tensor and then resize it to the appropriate size using tf.image.resize.

Second, the pixel values of the input images are typically encoded as integers in the range 0-255, but the model expects the pixel values to be floats in the range 0-1. Therefore, you'll also need to normalize the pixel values.

Finally, convert your image back to a NumPy array using the .numpy() method.

# TODO: Create the process_image function
def process_image(image):
    # Convert the image to a TensorFlow tensor
    image_tensor = tf.convert_to_tensor(image, dtype=tf.float32)
    
    # Resize the image
    image_resized = tf.image.resize(image_tensor, (224, 224))
    
    # Normalize the pixel values
    image_normalized = image_resized / 255.0
    
    # Convert the image back to a NumPy array
    processed_image = image_normalized.numpy()
    
    return processed_image

To check your process_image function we have provided 4 images in the ./test_images/ folder:

• cautleya_spicata.jpg
• hard-leaved_pocket_orchid.jpg
• orange_dahlia.jpg
• wild_pansy.jpg

The code below loads one of the above images using PIL and plots the original image alongside the image produced by your process_image function. If your process_image function works, the plotted image should be the correct size.

from PIL import Image

image_path = './test_images/hard-leaved_pocket_orchid.jpg'
im = Image.open(image_path)
test_image = np.asarray(im)

processed_test_image = process_image(test_image)

fig, (ax1, ax2) = plt.subplots(figsize=(10,10), ncols=2)
ax1.imshow(test_image)
ax1.set_title('Original Image')
ax2.imshow(processed_test_image)
ax2.set_title('Processed Image')
plt.tight_layout()
plt.show()

Once you can get images in the correct format, it's time to write the predict function for making inference with your model.

Inference

Remember, the predict function should take an image, a model, and then returns the top $K$ most likely class labels along with the probabilities. The function call should look like:

probs, classes = predict(image_path, model, top_k)

If top_k=5 the output of the predict function should be something like this:

probs, classes = predict(image_path, model, 5)
print(probs)
print(classes)
> [ 0.01558163  0.01541934  0.01452626  0.01443549  0.01407339]
> ['70', '3', '45', '62', '55']

Your predict function should use PIL to load the image from the given image_path. You can use the Image.open function to load the images. The Image.open() function returns an Image object. You can convert this Image object to a NumPy array by using the np.asarray() function.

Note: The image returned by the process_image function is a NumPy array with shape (224, 224, 3) but the model expects the input images to be of shape (1, 224, 224, 3). This extra dimension represents the batch size. We suggest you use the np.expand_dims() function to add the extra dimension.

# TODO: Create the predict function
def predict(image_path, model, top_k=5):
    # Load the image using PIL
    image = Image.open(image_path)
    
    # Convert the image to a NumPy array
    image_array = np.asarray(image)
    
    # Preprocess the image
    processed_image = process_image(image_array)
    
    # Add an extra dimension to represent the batch size
    input_image = np.expand_dims(processed_image, axis=0)
    
    # Make predictions
    predictions = model.predict(input_image)
    
    # Get the top k predicted class labels and probabilities
    top_k_indices = np.argsort(predictions[0])[::-1][:top_k]
    top_k_probs = predictions[0][top_k_indices]
    top_k_classes = [str(label) for label in top_k_indices]
    
    return top_k_probs, top_k_classes

Sanity Check

It's always good to check the predictions made by your model to make sure they are correct. To check your predictions we have provided 4 images in the ./test_images/ folder:

• cautleya_spicata.jpg
• hard-leaved_pocket_orchid.jpg
• orange_dahlia.jpg
• wild_pansy.jpg

In the cell below use matplotlib to plot the input image alongside the probabilities for the top 5 classes predicted by your model. Plot the probabilities as a bar graph. The plot should look like this:

You can convert from the class integer labels to actual flower names using class_names.

# TODO: Plot the input image along with the top 5 classes

image_paths = [
    './test_images/cautleya_spicata.jpg',
    './test_images/hard-leaved_pocket_orchid.jpg',
    './test_images/orange_dahlia.jpg',
    './test_images/wild_pansy.jpg'
]

for image_path in image_paths:
    # Make predictions
    probs, classes = predict(image_path, reloaded_model, top_k=5)
    
    # Load the image using PIL
    image = Image.open(image_path)
    
    # Create a figure with subplots
    fig, (ax1, ax2) = plt.subplots(figsize=(10, 6), nrows=1, ncols=2)
    
    # Plot the input image
    ax1.imshow(image)
    ax1.axis('off')
    ax1.set_title(image_path.split("/")[-1])
    
    # Plot the predicted class probabilities as a bar graph
    ax2.barh(range(len(probs)), probs, align='center')
    ax2.set_yticks(range(len(probs)))
    ax2.set_yticklabels([class_names[str(int(class_label) + 1)] for class_label in classes])
    ax2.invert_yaxis()  # Reverse the order of the bars
    ax2.set_xlabel('Probability')
    ax2.set_title('Top 5 Predicted Classes')
    
    plt.tight_layout()
    plt.show()

!python predict.py --input C:\Users\sickcell\Documents\GitHub\intro-to-ml-tensorflow\projects\p2_image_classifier\test_images\cautleya_spicata.jpg --model flowers_model.h5 --top_k 3

start Prediction ...
[0.74653125 0.03988568 0.02821388]
['60', '23', '45']
['cautleya spicata', 'red ginger', 'wallflower']
End Prediction 

2024-03-19 13:27:12.600877: I tensorflow/core/platform/cpu_feature_guard.cc:142] Your CPU supports instructions that this TensorFlow binary was not compiled to use: AVX2

!python predict.py --input C:\Users\sickcell\Documents\GitHub\intro-to-ml-tensorflow\projects\p2_image_classifier\test_images\wild_pansy.jpg --model flowers_model.h5 --category_names label_map.json

start Prediction ...
[0.93551224 0.01032172 0.00992055 0.00708438 0.00500734]
['51', '18', '63', '33', '81']
['wild pansy', 'balloon flower', 'silverbush', 'mexican aster', 'clematis']
End Prediction 

2024-03-19 13:27:17.981020: I tensorflow/core/platform/cpu_feature_guard.cc:142] Your CPU supports instructions that this TensorFlow binary was not compiled to use: AVX2

!python predict.py --input C:\Users\sickcell\Documents\GitHub\intro-to-ml-tensorflow\projects\p2_image_classifier\test_images\orange_dahlia.jpg --model flowers_model.h5 --category_names label_map.json

start Prediction ...
[0.22435921 0.20825194 0.08265641 0.0656297  0.04652524]
['58', '4', '65', '70', '99']
['orange dahlia', 'english marigold', 'osteospermum', 'gazania', 'blanket flower']
End Prediction 

2024-03-19 13:30:51.867768: I tensorflow/core/platform/cpu_feature_guard.cc:142] Your CPU supports instructions that this TensorFlow binary was not compiled to use: AVX2